2016-12-08 (Th) Clockwork Theremin

One time, years ago, I used a pipe cutter to trip a potentiometer handle. Potentiometer handles are often aluminum (aluminium) so they’re soft metal. It worked but it was time-consuming. My hacksaw was in my car trunk and I didn’t want to run out into the cold so I thought I would use the old trick.

 Using a pipe cutter on the potentiometer shaft

A pipe cutter was not the correct tool. It put unnecessary stress on the potentiometer, which didn’t break, and it was a waste of time. If the potentiometer shaft was clamped into a drill and spun it may have been a good time-gamble but that was not an option. After making my hand very sore I conceded that I had lost the time-gamble and went to my car trunk. There I discovered that the hacksaw was not in my trunk, it was in a storage box a couple feet from my pipe cutter. I should have used the correct tool the first time.

 Using a hacksaw on the potentiometer shaft

A 2” (50mm) bolt was purchased to replace the needlessly long bolt acting as the gear shaft. The only reason for a shorter bolt was to reduce the clearance from the gear board. The printed adapter was threaded onto the shaft by twisting it on the threads. This was photographed. The potentiometer was pushed into the adapter and bolted in place.

Adapter on the gear shaft

An animation showing the changing resistance and gear position was taken. Ideally, the animation would have used an analog meter display but a DMM with numerals and segments along the bottom was available. The potentiometer was logarithmic so the resistance climbed exponentially. This may require an exponential/logarithmic conversion in the programming.


Changing resistance and gear position

Downloads:
Parts list:

The rest of the posts for this project have been arranged by date.

First time here?


Completed projects from year 1.

Completed projects from year 2.

Completed projects from year 3.


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2016-12-08 (Th)

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